Control system for single-phase motors



APPLICATION FILED FEB I3, 1917.

Patnted Aug 1, 1922.

. 7.SHEETS-SHEET 1- vv vvvv n n p h n I n l I I p n I n n n n I o N VWITNESSES:

RLE. H ELLMUND CONTROL SYSTEM FOR SINGLE PHASE MOTORS.

"APPLICATION FILED ms. 13; 1911.

- Patented Aug. 1, 1922.

Y'sHEETs-sHEE 2.- F/ ,3

INVENTOR ATl'bRNEY S WITNESSES:

w gww R. E. H-ELLMUNII' CONTROL SYSTEM FOR SINGLE-PHASE MOTORS;

APPLICATION FILED FEB.13-, 1917- Patented Aug. 1, 1922;

7 SHEETS-SHEET 3.

WITNESSES; INVENTOR AT'TbRNEY R. E. HELLMUND.

CONTROL SYSTEM FOR SINGLE PHASE MOTORS.

APPLICAHON FI LED FEB. 13. 1917.

ISHEVETSQ-SHEET 4.

1,424,300, Patented Aug. 1,1922.

Fig, /5

H9 /6 Hg, /7

INVENTOR R. E. HELLMUND. v CONTROL SYSTEM FOR SINGLE PHASE MOTORS.

APPLICATION, FILED FEB. 13. 19 1.7.

Patented Aug. 1, 1922.

7 SHEETS-SHEET 5- INVENTOR Fwa/f f; //?///77L//70' WITN'ESSES:

ATTORNEY R. E. HELLMUND.

CONTROL SYSTEM FOR SINGLE PHASE MOTORS.

APPLICATION FILED FEB I3. 19!?- I Patented Aug. 1, 1922.

I I' l INVENTOR Fwo/f 5 Hal/277m WITNESSES:

R; E HELLMUNIL CONTROL SYSTEM FOR SINGLE PHASE. MOTORS.

APPLICATION FILED Puma. 1917.

1 ,424300. Patented Aug. 1, 19,2

7 SHEETS SHEET.7

WLTNESSES: r

ATTORNEY UNITED STAT E S PATENT OFFICE- RUDOLF'E. HELLMUND, or swIssvAn. PENNSYLVANIA, ASSIGNOR "1'0 WESTING- HOUSE ELECTRIC AND MANUFACTURINGCOMPANY, A CORPORATION OF YENN- SYLVAN IA.

CONTROL SYSTEM non sI'NenrirHAsE MOTORS.

Specification of Letters I'atent. Patented Aug; 1, 1922 Applicationfiled February 13,1917; Serial No. 148,418.

To all whom may concern:

. it known that I, Become E. HELLMUND, a subject oi the Emperor ofGermany, and s "tsident of Sivissval in the county of egheny and Stateof Pennsylva ia, have invented a new and useful Improvement in Control.Systems" for Single-Phase Motors, o l. which the following is aspecification.

,lilv invention relates to systems of control-"lor alternating-currentmotors of the commutator type. and it haslor its object rent motor Oilthecommutatortype, together with appropriate supply and control circuits and auxiliary apparatus embodying one form of my invention; Figs.2. to 10, inclusive, are simplified. diagrammatic views oi? the systemof Fig. 1, illustrating the development in the connections thereof Figs.11,, 20 and 21 are diagrammatic views of modifications of: the systemshown in Fig. 1; Figs. 19 to. 19, .inclusive are simplified diagnunnltlC viewsillustrating the development o l LllB connections in thesystem ofFig. l1; and hips. 22 to 30, inclusive, are simplilieddiagrammatlc views illustrating the tie velopment of the connections in.the system. of Fig. 21. The use of prevemlive reactors, in. conneclionwith controlv systems tor? alternatingcurrent motors is well-l. ;no\vn.Such reactors are prnerally made in the: form of anind-uc tive Windingwhich is bridged across adjacent taps in the supply source and which, inturn, tapped at. substantially its midpoint by a lead to the motor. Thereactor is thus highly inductive to current attempting to tlowironi onesupplytap totheother but is essentially non-inductive to equal amounts ol? current flowing from each tap to the motor. 1

By my invention, I provide means Where bv :i r ctor of the characterdesignated sii mo. ed that, not only mavit be employed, at times, as apreventive dcvicebut,

at other times, it may be employed as an auto-transformer tomodify thevoltage applied to the motor.

It is Well known that, in the acceleration of alternating-currentcommutator'motors, it isdesirable to provide a relatively strong crossfield at starting in order to compensate for the electromotive (forceestablished in: the

short-circuited armature coils undergoing commutation by transformeraction from the main-field Winding. Saidnstrong cross field is alsodesirable with many of the accelerating steps 'vvherewith largecurrentfloW temporarily takes place through the motor.

lVith many oi the running positions, however, the: current throughthei'motor. is com parativelysmall, after the vehicle has beenaccelerated tothe corresponding speed, and it is desirable,undertheseconditions, that the CIOSS'IIBIQl strength be limited in value.

In accordance with my present invention, I provide, means whereby,particularly in systems involving automatic acceleration, the crossfield is rendered comparatively strong during accelerating points and isrendered comparatively week during run-' ning points. lfiurtherinore, Imay provide means whereby the change-over from the usual repulsion orreversed doubly-fed starting connection to the subsequent doubly-fedrunning, connection may be causedto take place at diiferenttimes inaccordance with the line voltage. "thus ensuring that the motor shallnot go into the doubly-fed connection unless the line voltage issufficiently high toprovide the proper cross-field eXcitation. Thislatter feature per se is described in a copending application of H. T.Morris, Serial No. 32,188, filed June 4,1915, ainfl assigned to theWestinghouse Electric is lllanufacturing Company. Said control feature avaluable adjunct tothe present 1 system, however, and I shall,therefore, de- SlCll'JG it in combination therewith.

Relerringto the lrawinglfor a more detailed understanding ofmyinvention, I show an alternating current motor of the single-phasealternating-current motor compensated commutator type at 25,. in Fig. 1.Said motor embodies a magnetizing-field Winding 26, an armature 97 and across. or

inducing-field Winding 28-. Energy for the.

operation of the motor "25ls' derived? from any suitablesource,such,.lf.or.example, the secondary winding 29- of transformer 30.

The voltage applied vto the outer terminal. of the cross-field winding28 may be adjusted by means of a plurality of switches l to (5,inclusive, and a preventive reactor 31. An intermediate tap for doubly-led operation may be established to one terminal of the magnetizing-fieldwinding 26 through a switch 15 or to the other terminal, of saidmagnetizing-field winding through a switch 16. The voltage supplied tothe switches l5 and 16 is under the control o'lf suitable switches 7, 8,and 9 and of a composite pre ventive reactor The voltage supplied to theouter armature terminal is controlled by a switch 10, and the armature27 may be short circuited 't'or repulsion operation by a switch 14.

The switches l to 16, inclu:-'i. e, may be of any desired type, eithermanually operative or electrically or pneumatically operated from asuitable master controller, all as is well known in the art, thespecilic type of switches employed forming no part of the presentinvention. For purposes o'l illustration, l have shown the switches l to16, inclusive, as of the electrically-operaled type, under the controlof a controller 33 which may be manually operated or which may beautomatically operated, by a PK head 50 subject to a current-limitswitch shown at L For simplicity and clearness of illustration, 1 haveomitted. the return leads of the energizing coils of the dilierentswitches terminating said leads at a sign and applying a sign to theappropriate side of the control battery, as is well understood in theart.

in connection with the controlle 22, ill? teen positions are indirated.those designated by A. being for acceleration only, those by 'i. Fortransition only and those by it lior running.

l laving thus described the arrangement o'l a system embodying myinvention, the op-- oration is as :lollows. in the first acceleratingposition, the switches 5, (5, 9, let and 16 are closed, whereupon theconnections shown in l ig. 2 are established. The motor is connectedilor repulsion operation. with a minimum voltage illlplQSflOd thereuponand,

with the right-hand third of the device 32 used a a current limitingreactor. in the cult, thus effecting a smooth transition Said positions3 and t are merely for tranlield winding supplied with the cross-fieldcurrent. Because of the usuai two to one ratio between the turns oi? thecross-held winding, this connection results in the relatively weakmagnetizing lield netcesitatcd by the commutating conditions. Forfurther arceleration, the intermediate tap should now be translhrred tothe inner terminal oi the cro s-held wimling so that themagnetizing-lield winding mav be energized in accordance with thearmature current. For this purpose, the switch l5 is closed, as.indicated in pOsition 8, establishing the connections of Fig. T. Theright-hand twothirds ol? the device 32 is connected in parallel with themagnetizing-field winding :26

and the mid point of said active portion ol the device 32 is connectedto the supply ource. in position 9, indicated in Fig. 8,

the transition to the l'inal type of doublydied ctnmertion is completed,the switch .16 being open and the middle third ol? the device 352operating as a c1lrrent-lii'uiting reactor. For further acceleration ol,the motor, the voltage on the intermediate tap is raised by the closureoi the switch 8, as shown in posh tion 10. The left hand two-tl'iirds olthe device 32 now operates as an ordinary preventive coil.

For the concluding running positions, the voltage applied to the outerterminal of the cross-field winding is iurreiumd by the propermanip'ulatim'i oi? the switclws l to (L inclusive, and, in the inalposition. the switch 9 is opened and the switch T is (loscd. thuslin-idging the le'lthan-zi two-thirds ol' the device 32 across a newportion at the trauscformer winding and raising the voltage ap plied tothe intermc iliate tap.

From the foregoing, it will broln'ious that the device 32 functions inthree distinct ways. In the place, dillmeut portions the eof arecnugloyed solely as current-limit ing reactors; in. the second place,said device employed as an auto-transFormer lor raising the voltage; andin-ally. said device is employed solely as a, n'eveulivc reactor ol' theordinary type.

Referring to the form of my invention ill) shown in Figs. 11 to 19,inclusive, an alternatmg-current commutator motor isshown at 25, in allrespects similar to the corre sponding apparatus in the system ofFig. 1. and deriving energy from a similar source 29. A reactor 32 isshown which, in addi-.

tion to the connections shown in Fig. 1, may also have its upper thirdshort-circuited by a switch 17. A controller 34-, in many respectssimilar to the controller 33 oi Fig. 1, is provided but additional meansare incorporated therewith whereby the accelerating sequence in the lastfivepositions is under the control of the load current, as determined bya limit switch L As shown, said effect is produced by providing twoauxiliary energizing contact members 35 and 36 upon the control drum andby causing the member 35 to be energized only when the load current iscomparatively heavy, under which conditions the limit switch L is up,and, by causing the segment 36 to be energized only when the loadcurrent is comparatively small and the limit switch is accordingly down.As a result of the operation ofthe limit switch L the cross-fieldwinding receives a relatively large current supply and the armature arelatively small applied voltage under heavy-current conditions,whereas, with light-load current, the voltage applied to the armature isincreased and that applied to the cross-field winding is decreased.

It will be understood that the specific means illustrated for obtainingthis load-current eiiect are simply diagrammatic and are provided forpurposesoi illustration only, there being a wide variety of possiblecon: trol systems available whereby the specific results in question maybe obtained as, for example. by suitable interlocking between therespective switches, etc. As the present invention is directedprincipally to the method of accelerating the motor: and issubstantially independent of the specific means whereby said control.sequence is obtained, I have deemed it unnecessary to complicate thecontrol bya showing of other control systems that might be available.Having thus described the arrangemetnt of the system shown in F ig. 11,the operation thereof is as :tollows. In the first position, theswitches 52, 3, 11, 12, 1d and 16 are closed, establishing theconnections shown in Fig. The armature is short-circuited tor repulsionoperation, the upper portion oi the device is connected. across aportion of the trans- ;t'ormer and the lower terminal oi said device isconnected to the inner armature ter minal, the reactor 32 thus acting asan auto transformer, lowerii'lgthe voltage applied to the motor..frelatively low voltage isapplied to the outer cross-field. terminal.In the second position, the switch 11 is open, so alteringtheconnectionsto, the reactor 32 that the lower portion thereof operates as strongcross field, whereas the connections of a current-limiting device, theresult heirs an increase in the total voltage a the motor, all asindicated in Fig. 13.

The outer terminal. of the armatureis next connected directly to theright-hand terminal of the source 29 by the closure of the switch 13 andthe connection through the device 32 is then removed, the voltageapplied to the outer terminal cross-field winding at the same time beingraised, as indicated in Figs. 14 and 15. i

In the sixth'accelerating position, preparations are made for changingover to doublyfed operation by reintroducing the lower third of thedevice 32 as a current-limiting reactor, as indicated in Fig. 16, andthe switch 14; is then opened to remove the repulsion connection, asindicated, in Fig. 1'? and the seventh accelerating position.

To transfer from doubly-fed operation. with cross-field current in themagrnetiZingfield winding, to doubly-fed operation, with armaturecurrent in the maghetizing-iield winding, the device 32 is used as atransition device and the upper portion thereof is then used as apreventive device in raising the voltage on the intermediate tap, as 1indicated in Fig. 18.

The sequence just described in connection with 18 obtains only withsuchheavy load current that the limit switch L is held in its upperposition. It the load current be so small in the tenth, twelfth andtourteenth accelerating positions that the limit switch L falls, thevoltage impressed upon the outer terminalofthe cross-field winding isreduced in value from that obtaining with heavy load current and theswitch lff is simultaneously closed, short-circuiting the upper portionof the device 32 and connect- 111g the inner cross-field terminaldirectly to the supply source, thus, in effect. raising the armaturevoltage while reducing thecrossfield voltage. v

The connections indicated in Fig. 18 are obviously better adapted foroperation with heavyload current as the commutating con ditions are suchas to demand a relatively Fig. 19. are better adapted. for light-loadcurrent operation,wherewith a much weaker cross field is permissible.

It will be noted that the connections of Fig. 19 are established only inthe tenth,

twelfth, and, fourteenth accelerating positions, which are those adaptedfor use as running positions under light-load conditions. The eleventhand thirteenth positions, while adapted for continuous running withheavy-load current, are intended only as accelerating positionswithlight current and.

as the current is much heavier during the acceleration of :a given loadthan during subsequent running therewith, it is advisable that theswitch 17 be not closed during the which the tune of transition. :1, Lto doubly-led operation is v armally mined in accordance with the huevoltag motor 25, designated SiTlliliUl to c1 i urcsu respondingapparatus in the ruacr iii receives its enem from the solute. 115$)tln'cngl'i appropriate switching dei 'i: Controller 37 is provided andth 1m cor Jorated therewith a oluralit 1 l J n oi" energii w ingsegments 38 to 4-2, llll in addition to the usual battery-onergnzin;segment The currei'it-liini't switch if has its cuei iug winding inseries with the cross-l'icl "ifillltflll'lg, and the voltage-limitswitch 1'. has its energihing winding; cormected across the terminals ofa cross-field \llllllllg. tluitable switch members are ac tuatc l by thedevices it and and are connected in sir-h manner that, in the last fouraccclcrating positions, the segment 38 is energized with L up and lifiup; the segn'ient 39 with l)" up and L down; the segment l-l) with up;the segment 41 i 'v'ith IF down; and

segment 42 with either if up and ii" up The SBQjlni-ElllS with L down. vno to clusi've, are coiniccted to their various con i segments which areactive in the last rowpositions by any suitable means iinilicated at n.

The acceleration up thro igh the elex-erth position is similar to that:ilrca For the twelfth accelerating; position. um normal line voltageand L up, it is d i that the motor be operating doubly; accori'linglyunder these conditions the switches l3, 3 and Z are closed directly bybattery current and the switches h ll ill 15 are energized tlroni thesegment 2-58. ll line voltage is low it is desirable that re pulsionoperation he continued and ti eretore, the switches l6 and 14; areclosed roni the segment 39, the switches: ML 11, and 1:3 openingbecauseof the de-energization ol the segment 88.

In the thirteenth accelerating position. it is desirable that theoperation be of the doubly-ted character. with normal or heavyloadcurrent and th reasonably high rul that it remain douhlyd'ed i'l' theload current is snialh even although the line voltage drops abnormally,hut that it repulsion type it the load current is normal or heavy and itthe line vohzage drops ahnormally. The switch 1, partially control--ling the voltage applied to the outer cross- Field winding, shouldremain closed OXPOPI/V under conditions oil abnormally low current l'oliin hie voltzi Y l i field tern nuial is closed. a all ti therefore,is energized dn ii troni the battery segrnient 4&3. The so itch ll, ap'iilying a lower volt 5e to the outer term nal of the jl'OSF-il 3l(llWillljllllg than the switch 1, is closed only u der conditions o'l lightload current 1 1d I there ore, en im-d 'l l' jrill the segment 4-1. Theswitch 5) is; controlled in a l 1:5 and if} ls closed with lienry loailcurrent owl normal line voltage of with light-load curthe line voltagebut nilnr niani'icr.

l he opened with 1 orinal or licavydoa l urrent and abnornu lly low linevoltaec. t aid switches are, there/tore, energize 'l from 'cgzneut Theswitch ll closed er nn'inll-loa 'l current and "s, there'lore energisedfrom the semnent ill The switches l t and i6 are closed. with normal orheavy line current under all voltage condi tions and ari energized lronithe segment 39. merely an accelin position mi-A which is rntir ,2position, it is ciscntial that a strong rinse-mid he nniiulninod underall condill) iii and to battery cur i the s n the horn l t l resulted attimes in a strength ol substantially l strength This weal:maguiulcsirahle for some of the s it ill-annuals on much armant. L lllScllccli may he done away innug liel- '1 M w ncr speeds lure cur!" ithand the inductive c. l the magnetnn -l'ield whir ing properly l' ributedin acmi'dance with any dcsirei' rzmo by means ol the sy can disclosed inl .g'. L A motor Eli? having; its ('Olililt iltllil parts d csignated asin l ig. l is energised lroni a source :29 llllOlll lfll suitshlecontrol switches and a re actor 31%. llCl reactor tapped at each end andat two inlei'niecliate points. (laid taps are dmignated as to -19inclusiwi as indicate c' 'feririugg to Figs 92 to Ill) to a detaileddescription of the method o'l acceleration employed in the system or yl, the mvitches 5, (5 1?, lcl and ill are closed in the li taccelei-lifting notch, establishing a 1"V6lSb douhlyd ed chi'inection,as shown in Fig. 22. In the second acwleratmg notch,

the switch 1 is closed, raising the voltage on switches 9 and areclosedand, in the position, the switch 18 is opened,

*ansifcrring from the reverse doublyfed connection oi 22 to the ordinarydoubly-ted connection of Fig. 523, the portion of the preventive devicewhich is included between the taps 41-5 and 46 being included in theintermediate lead as a currcnt-limiting device. The intermediatedoublyded tap is connected to the inner armature terminal. acceleratingpositions. the switch 16 p is opened and the switches 15 and 17 areclosed, producing the connections of Fig. 24:. The motor is arranged tordoubly-ted operation, with the intermediate tap connected to the innercross-field terminal, thus raising the armature voltage. The portion ofthe device 32 which is included between the taps 46 and 11-7 is insertedin the intermediate tap as a current-hmiting device. In the seventhaccelerating position, the switch 19 is opened, thus causing the portiono'l" the device $32 which is included between the taps 457 and 48 to beinserted in circuit with the cross-field winding. In the eighth andninth accelerating position, the switch 5 is opened, the switch 3 isclosed and again opened and the switch 6 is again closed, establishingthe connections of Fig. 26, which con. actions require special mentionas they illustrate a novel use of the inductive device 32. The tap 45 isconnected to the inner armature terminal, the tap 16 to the source, thetap a? to the outer main field terminal and the tap 48 to the innercross-fieldterminah The voltage between the taps 15 and 47 is that ofthe main field winding and, assuming that the taps in the member 32 areequally spaced, there is produced, by transformer action in the portionof the reactor 32 which is included between the taps 4:7 and 18, anelectromotive force which is substantially one-halt of the main-fieldvoltage. Said portion of the reactor 32is included in series with thecrossfield winding and said transformer voltage is, therefore, added tothe cross-field voltage, The usual 2 to 1 transformer ratio existingbetween the cross-field winding and the armature winding thus producesan additional counter voltage in the armature winding equal tosubstantially one-quarter of the main field voltage. Thus, the inductiveeitfect of the main field winding is distributed between the cross-fieldwinding and the armature winding. By varying the diflerent points 01.attachment of taps 4-5 0048,.

inclusive, said main field inductive effect may be distributed inaccordance with any desired predetermlned ratio.

In the twelfth and thirteenth accelerating in the fifth and sixth In thetenth accelerating position, the switch- 16 is opened, producing theconned tions of liig. :27. The portion 4t6-l8 o'fthe .ctor is active,serving as an auto-transice in impressing an intermediate voltupon thearmatiu'e and main-field voltj in the eleventh position, the switch19 jr" oscd, tempmfarily' establishing the con- .ions of Fig. which are the:same as those of F 2 1 except for the high voltage.

impress d upon the outer cross-field windin.

positions, assuming heavy-load current so that the limit switch L is up,the final running connections shown in Fig. 29 are established. Theswitches 1, E2, 8, 9, 13, 15 and l are closed and the motor is connectedfor doubly-ted operation, with the intermediate tap connected to theinner cross-field terminal. The points to and 48 of the reactor 32 areconnected to spaced points in the source, and the intermediate point l?is connected to the or a lield terminal so that the portion G4ltl i thereactor 32 acting as an ordinary prevcnti m device. It the load currentdecreases to such an extent that the limit switch L falls, the switches1, 9 and 13 are opened and the switches 3 and F are closed.

Tl'ius, the armature voltage is slightly raised by the movement oi theintermediate point ot attachment tmvard the left, and the cross field'oltage is lowered, not only by said movement at the intermediate tapbut also by the reduction of the voltage applied to the outer oss tieldtap. Thus, the proper commutat coi'iditions are established tor thelight-load current in question.

Whi e I have shown my invention in a tv olf torn it will. be obvious tothose red in the art that it is susceptible of va rious otheralterations and modifications without departing irom the spirit thereofand I desire, therefore, that only such limitations shall be placedthereupon as are imposed by the prior art orare specifically set forthin the appended claims.

I claim as my invention:

1. The method of energizing a dynamoelectric machine of the commutatortype provided with a cross-field winding, said machine being associatedwith a source of alternating-current, a reactor, and suitable switchingmeans therebetween to establish a doubly-ted system oi connectionsincluding an intermediate tap, which comprises, at times, employing saidreactor as a preventive device, at other times employing said reactorsolely a. current-limiting reactor,

of alternating current, a reactor, suitable switching means andconductors therebetween to establish a doubly-l ed system of connectionsincluding an intermediate tap, which comprises, at times, employing saidreactor solely as a current-limiting device in adjusting the voltagesupplied to said intermediate tap, at other times, employing saidreactor as a preventive device in adjusting the oltage supplied to saidintermediate tap and, at still other times employing said reactor as anauto-transformer in adjusting the voltage supplied to said intermediatetap.

In testimony whereof, I have hereunto subscribed my name this 31st dayoi Januau'y i917. ,7

RUDOLF E. HELLMUND.

